"The No. 1 mistake is not putting down the right Social Security numbers, and the second is not doing the right math," said Thomas Cooke, professor of accounting and business law at Georgetown University.
It may be worth hiring a preparer to handle your return or walk you through the process, Cooke said.
"In tough economic times, people may be getting away from professionals," said Cooke. "And as more and more people do their taxes on their own, there will be more mistakes -- both in terms of math errors and the deductions that are taken."
Take the time to double-check everything if you're filling out your own return, and if you decide to use tax software to file, make sure you understand how to use it, Cooke advised.
From pet pigs to Playboy magazines, here are some of the most outlandish deductions taxpayers have tried to slip past the IRS.
|Greece Crisis 101: No way out|
|China spends billions to prevent stock market crash|
|Why China's crazy stock market is getting scary|
|Greece deeply divided as vote on Europe looms|
|What a Depression looks like (Greek style)|